Touchpads make use of capacitive sensing, conductive sensing, or other technologies to map an input received by a touchpad to movement of a cursor, for example. A user can interact with a touchpad by sliding a finger along a touch-sensitive surface to control a cursor on a display. Additionally, some touchpads include the ability to sense and interpret tapping motions or other movement gestures indicating execution of a function by a computing device coupled to the touchpad.
A common method of operating touchpads involves sensing capacitance levels of a two-dimensional grid array of capacitors. A high frequency signal is applied to two layers of parallel lines, crossing each other at rights angles, and separated by an insulator forming the grid array of capacitors. Objects near intersections of the grid create changes in capacitance at the intersections, which are processed to determine position and movement information.